import 'dart:typed_data';
import 'package:file_selector/file_selector.dart' as fs;
import 'package:flutter/foundation.dart' show kIsWeb;
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:pdf_signature/l10n/app_localizations.dart';
import 'package:printing/printing.dart' as printing;

import '../../../../data/services/providers.dart';
import '../view_model/view_model.dart';
import 'draw_canvas.dart';
import 'pdf_toolbar.dart';
import 'pdf_page_area.dart';
import 'adjustments_panel.dart';
import '../../preferences/widgets/settings_screen.dart';

class PdfSignatureHomePage extends ConsumerStatefulWidget {
  const PdfSignatureHomePage({super.key});

  @override
  ConsumerState<PdfSignatureHomePage> createState() =>
      _PdfSignatureHomePageState();
}

class _PdfSignatureHomePageState extends ConsumerState<PdfSignatureHomePage> {
  static const Size _pageSize = SignatureController.pageSize;

  // Exposed for tests to trigger the invalid-file SnackBar without UI.
  @visibleForTesting
  void debugShowInvalidSignatureSnackBar() {
    ref.read(signatureProvider.notifier).setInvalidSelected(context);
  }

  Future<void> _pickPdf() async {
    final typeGroup = const fs.XTypeGroup(label: 'PDF', extensions: ['pdf']);
    final file = await fs.openFile(acceptedTypeGroups: [typeGroup]);
    if (file != null) {
      Uint8List? bytes;
      try {
        bytes = await file.readAsBytes();
      } catch (_) {
        bytes = null;
      }
      ref.read(pdfProvider.notifier).openPicked(path: file.path, bytes: bytes);
      ref.read(signatureProvider.notifier).resetForNewPage();
    }
  }

  void _jumpToPage(int page) {
    ref.read(pdfProvider.notifier).jumpTo(page);
  }

  // mark-for-signing removed; no toggle needed

  Future<void> _loadSignatureFromFile() async {
    final typeGroup = const fs.XTypeGroup(
      label: 'Image',
      extensions: ['png', 'jpg', 'jpeg', 'webp'],
    );
    final file = await fs.openFile(acceptedTypeGroups: [typeGroup]);
    if (file == null) return;
    final bytes = await file.readAsBytes();
    final sig = ref.read(signatureProvider.notifier);
    sig.setImageBytes(bytes);
    // When a signature is added, set the current page as signed.
    final p = ref.read(pdfProvider);
    if (p.loaded) {
      ref.read(pdfProvider.notifier).setSignedPage(p.currentPage);
    }
  }

  void _createNewSignature() {
    // Create a movable signature (draft) that won't be exported until confirmed
    final sig = ref.read(signatureProvider.notifier);
    if (ref.read(pdfProvider).loaded) {
      sig.placeDefaultRect();
      ref
          .read(pdfProvider.notifier)
          .setSignedPage(ref.read(pdfProvider).currentPage);
      // Hint: how to confirm/delete via context menu
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(
          content: Text(
            'Long-press or right-click the signature to Confirm or Delete.',
          ),
          duration: Duration(seconds: 3),
        ),
      );
    }
  }

  void _confirmSignature() {
    // Confirm: make current signature immutable and eligible for export by placing it
    ref.read(signatureProvider.notifier).confirmCurrentSignature(ref);
  }

  void _onDragSignature(Offset delta) {
    ref.read(signatureProvider.notifier).drag(delta);
  }

  void _onResizeSignature(Offset delta) {
    ref.read(signatureProvider.notifier).resize(delta);
  }

  void _onSelectPlaced(int? index) {
    ref.read(pdfProvider.notifier).selectPlacement(index);
  }

  Future<void> _openDrawCanvas() async {
    final result = await showModalBottomSheet<Uint8List>(
      context: context,
      isScrollControlled: true,
      enableDrag: false,
      builder: (_) => const DrawCanvas(),
    );
    if (result != null && result.isNotEmpty) {
      // Use the drawn image as signature content
      ref.read(signatureProvider.notifier).setImageBytes(result);
      // Mark current page as signed when a signature is created
      final p = ref.read(pdfProvider);
      if (p.loaded) {
        ref.read(pdfProvider.notifier).setSignedPage(p.currentPage);
      }
    }
  }

  Future<void> _saveSignedPdf() async {
    // Set exporting state to show loading overlay and block interactions
    ref.read(exportingProvider.notifier).state = true;
    try {
      final pdf = ref.read(pdfProvider);
      final sig = ref.read(signatureProvider);
      // Cache messenger before any awaits to avoid using BuildContext across async gaps.
      final messenger = ScaffoldMessenger.of(context);
      if (!pdf.loaded || sig.rect == null) {
        messenger.showSnackBar(
          SnackBar(
            content: Text(AppLocalizations.of(context).nothingToSaveYet),
          ), // guard per use-case
        );
        return;
      }
      final exporter = ref.read(exportServiceProvider);
      final targetDpi = ref.read(exportDpiProvider);
      final useMock = ref.read(useMockViewerProvider);
      bool ok = false;
      String? savedPath;
      if (kIsWeb) {
        // Web: prefer using picked bytes; share via Printing
        Uint8List? src = pdf.pickedPdfBytes;
        if (src == null) {
          ok = false;
        } else {
          final processed = ref.read(processedSignatureImageProvider);
          final bytes = await exporter.exportSignedPdfFromBytes(
            srcBytes: src,
            signedPage: pdf.signedPage,
            signatureRectUi: sig.rect,
            uiPageSize: SignatureController.pageSize,
            signatureImageBytes: processed ?? sig.imageBytes,
            placementsByPage: pdf.placementsByPage,
            targetDpi: targetDpi,
          );
          if (bytes != null) {
            try {
              await printing.Printing.sharePdf(
                bytes: bytes,
                filename: 'signed.pdf',
              );
              ok = true;
            } catch (_) {
              ok = false;
            }
          } else {
            ok = false;
          }
        }
      } else {
        // Desktop/mobile: choose between bytes or file-based export
        final pick = ref.read(savePathPickerProvider);
        final path = await pick();
        if (path == null || path.trim().isEmpty) return;
        final fullPath = _ensurePdfExtension(path.trim());
        savedPath = fullPath;
        if (pdf.pickedPdfBytes != null) {
          final processed = ref.read(processedSignatureImageProvider);
          final out = await exporter.exportSignedPdfFromBytes(
            srcBytes: pdf.pickedPdfBytes!,
            signedPage: pdf.signedPage,
            signatureRectUi: sig.rect,
            uiPageSize: SignatureController.pageSize,
            signatureImageBytes: processed ?? sig.imageBytes,
            placementsByPage: pdf.placementsByPage,
            targetDpi: targetDpi,
          );
          if (useMock) {
            // In mock mode for tests, simulate success without file IO
            ok = out != null;
          } else if (out != null) {
            ok = await exporter.saveBytesToFile(
              bytes: out,
              outputPath: fullPath,
            );
          } else {
            ok = false;
          }
        } else if (pdf.pickedPdfPath != null) {
          if (useMock) {
            // Simulate success in mock
            ok = true;
          } else {
            final processed = ref.read(processedSignatureImageProvider);
            ok = await exporter.exportSignedPdfFromFile(
              inputPath: pdf.pickedPdfPath!,
              outputPath: fullPath,
              signedPage: pdf.signedPage,
              signatureRectUi: sig.rect,
              uiPageSize: SignatureController.pageSize,
              signatureImageBytes: processed ?? sig.imageBytes,
              placementsByPage: pdf.placementsByPage,
              targetDpi: targetDpi,
            );
          }
        } else {
          ok = false;
        }
      }
      if (!kIsWeb) {
        // Desktop/mobile: we had a concrete path
        if (ok) {
          messenger.showSnackBar(
            SnackBar(
              content: Text(
                AppLocalizations.of(context).savedWithPath(savedPath ?? ''),
              ),
            ),
          );
        } else {
          messenger.showSnackBar(
            SnackBar(
              content: Text(AppLocalizations.of(context).failedToSavePdf),
            ),
          );
        }
      } else {
        // Web: indicate whether we triggered a download dialog
        if (ok) {
          messenger.showSnackBar(
            SnackBar(
              content: Text(AppLocalizations.of(context).downloadStarted),
            ),
          );
        } else {
          messenger.showSnackBar(
            SnackBar(
              content: Text(AppLocalizations.of(context).failedToGeneratePdf),
            ),
          );
        }
      }
    } finally {
      // Clear exporting state when finished or on error
      ref.read(exportingProvider.notifier).state = false;
    }
  }

  String _ensurePdfExtension(String name) {
    if (!name.toLowerCase().endsWith('.pdf')) return '$name.pdf';
    return name;
  }

  @override
  Widget build(BuildContext context) {
    final isExporting = ref.watch(exportingProvider);
    final l = AppLocalizations.of(context);
    return Scaffold(
      appBar: AppBar(title: Text(l.appTitle)),
      body: Padding(
        padding: const EdgeInsets.all(12),
        child: Stack(
          children: [
            Column(
              children: [
                PdfToolbar(
                  disabled: isExporting,
                  onOpenSettings: () {
                    Navigator.of(context).push(
                      MaterialPageRoute(builder: (_) => const SettingsScreen()),
                    );
                  },
                  onPickPdf: _pickPdf,
                  onJumpToPage: _jumpToPage,
                  onSave: _saveSignedPdf,
                  onLoadSignatureFromFile: _loadSignatureFromFile,
                  onCreateSignature: _createNewSignature,
                  onOpenDrawCanvas: _openDrawCanvas,
                ),
                const SizedBox(height: 8),
                Expanded(
                  child: AbsorbPointer(
                    absorbing: isExporting,
                    child: PdfPageArea(
                      pageSize: _pageSize,
                      onDragSignature: _onDragSignature,
                      onResizeSignature: _onResizeSignature,
                      onConfirmSignature: _confirmSignature,
                      onClearActiveOverlay:
                          () =>
                              ref
                                  .read(signatureProvider.notifier)
                                  .clearActiveOverlay(),
                      onSelectPlaced: _onSelectPlaced,
                    ),
                  ),
                ),
                Consumer(
                  builder: (context, ref, _) {
                    final sig = ref.watch(signatureProvider);
                    return sig.rect != null
                        ? AbsorbPointer(
                          absorbing: isExporting,
                          child: AdjustmentsPanel(sig: sig),
                        )
                        : const SizedBox.shrink();
                  },
                ),
              ],
            ),
            if (isExporting)
              Positioned.fill(
                child: Container(
                  color: Colors.black45,
                  child: Center(
                    child: Column(
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        CircularProgressIndicator(),
                        SizedBox(height: 12),
                        Text(
                          l.exportingPleaseWait,
                          style: const TextStyle(color: Colors.white),
                        ),
                      ],
                    ),
                  ),
                ),
              ),
          ],
        ),
      ),
    );
  }
}